From: Don Mullis Date: Thu, 30 Sep 2010 22:15:32 +0000 (-0700) Subject: lib/list_sort: do not pass bad pointers to cmp callback X-Git-Tag: v2.6.36-rc7~33 X-Git-Url: https://bbs.cooldavid.org/git/?p=net-next-2.6.git;a=commitdiff_plain;h=f015ac3edd84ad72f88e08a4d83c56c360aae404 lib/list_sort: do not pass bad pointers to cmp callback If the original list is a POT in length, the first callback from line 73 will pass a==b both pointing to the original list_head. This is dangerous because the 'list_sort()' user can use 'container_of()' and accesses the "containing" object, which does not necessary exist for the list head. So the user can access RAM which does not belong to him. If this is a write access, we can end up with memory corruption. Signed-off-by: Don Mullis Tested-by: Artem Bityutskiy Signed-off-by: Artem Bityutskiy Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/lib/list_sort.c b/lib/list_sort.c index 4b5cb794c38..a7616fa3162 100644 --- a/lib/list_sort.c +++ b/lib/list_sort.c @@ -70,7 +70,7 @@ static void merge_and_restore_back_links(void *priv, * element comparison is needed, so the client's cmp() * routine can invoke cond_resched() periodically. */ - (*cmp)(priv, tail, tail); + (*cmp)(priv, tail->next, tail->next); tail->next->prev = tail; tail = tail->next;